Electric switch



'April 15, 1930. v G. BR Ui -ILMANN 1,754,349

ELECTRIC SWITCH Filed Oct, 29, 1923 I MGM Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE GOTTFRIED BR'U'HLMANN, OF BADEN, SWITZERLAND, ASSIGNOR TO AKTIENGESELL- SCHAFT BROWN, BOVERI AND CIR, OF BABE-N, SWITZERLAND ELECTRIC Application filed October 29, 1923, Serial No.

Large surgings of electric currents, which occur more particularly in the case of shortcircuits in large networks, generate at the contacts of the electric switches situated in the circuit, electro-dynamic and thermic forces which seek to separate the switch contacts from each other. These forces are especially damaging on the closing of the circuit after an immediately previous short-circuit, because they are generated before the switch has been returned mechanism upon the cross-piece (1, must there- .fore be of such an amount that it will overcompletely into its closed position. In such a case it may happen that after the first contact is made an electric arc is formed at the switch contacts by which the switch is strained to excess.

With the object of obviating or at least, diminishing these electro-dynamic and thermic forces at the switch contacts, according to this invention special conducting devices such as for instance coils, are so located inside the switch to be protected, and so connected, as to cause its movable contacts to be pressed by electro-dynamic forces against its fixed contacts.

A practical embodiment of this invention is illustrated by way of example in the accompanying drawings in which:

Figures 1 and 2 are diagrammatic representations explaining the operation of the improved electric switch.

Figure 3 is an elevation partly in section of a practical embodiment of the invention.

Referring first to Figure 1:a, a represent the terminals of the improved switch; 5, 6 represent its fixed contacts and c, a represent its movable contacts; d represents a cross member carrying the movable contacts; 6, e represent springs which transmit the pressure produced by the operating mechanism from the cross-piece d to the contacts 7), b; 7, f represent two conductor portions fixed to the movable contacts; g, 9, represent two coils fixed to the cross-piece d; h, It represent two flexible connections between the conductor portions f and the coils g. The arrows indicate the direction of the current. The coils g generate in the interior of the coils a magnetic field, which, to an observer looking into the interior of the coils, appears to be di- SWITCH 671,583, and in Germany November 6, 1822.

rected away from him towards the plane of the paper. The forces exerted by this magnetic field upon the conductor portions 7 and by the latter upon the contact pieces 6, are directed upwards; consequently they press the movable contacts 0 against the fixed contacts b.

The reaction to the force exerted upon the movable contacts is taken, in this example, by the coils that is to say by the cross-piece d. The force which is exerted by the operating come the said reaction, or at least overcome the original electro-dynamic or thermic force exerted upon the contacts. This is generally the case. The springs e whose compression facilitates in general the separation of the contacts from each other, and consequently the formation of an electric are, are relieved of load by the force acting upon the co1'1- (luctors In many cases however the force which is exerted upon the cross piece d by the operating mechanism is not sufliciently great to offer sufiicient resistance to the repelling electro-dynamic and thermic forces that occur at the contacts when short-circuits take place. In such cases, according to this inventiomthe electro-dynamic forces which press the switch contacts together are produced between conductor portions that are connected mechanically to the fixed switch parts and to the movtacts b.

The reaction to the force exerted upon the movable contacts is taken in this case by the coils 7, that is to say, by the fixed part of the switch. By this arrangement the switch operating mechanism is relieved of load resulting from repelling forces produced by the large current at the contacts.

, viating' short-circuits or eddy currents in them.

The magnetic field of the conductor por tions which causes the electro-dynamic pressing'of the movable contacts against the fixed contacts, may in most cases be strengthened by the incorporation therewith of iron. For instance, in Figures 1 and 2 the coils 9 may be provided with iron cores with an air gap intervening. In this air gap an especially strong magnetic field would be generated, and in this field the conductors would move. Likewise in the example illustrated in Figure 3, the magnetic field may be strengthened by means of iron cores within the coils, or by means of bell-shaped iron shells or casings g outside the coils.

' What I claim is 1. In an electric switch, a pair of cooperating relatively movable contacts each provided with a series conductor portion in the form of a coil, said coils being similarly-wound, the respective contacts being formed as a split ring connected to the end of its own conductor portion.

2. In an electric switch, the combination with a pair of relatively movable cooperating contacts, of compressible similarly-wound coils supporting the contacts, said coils functioning as conductors which are energized in series with the contacts when the latter are together and cooperating to exert electrodynamic forces on the contacts resisting their separation.

' 3. In an electric switch, in combination, cooperating relatively movable contacts, and similarly wound coils forming extensible supports for the contacts, said coils being arranged to. be energized in series when the contacts are closed.

4. In an electric switch, in combination, a movable contact carrier, a contact support, co-

operating contacts carried on the support and 55 carrier, and similarly-wound coils connected in series with the contacts, said coils being arranged to exercise mutually attractive influences when energized.

* 5. In an electric switch, in combination, cooperating relatively movable circuit closing contacts, and similarly-wound coils forming supports for the contacts, said coils being arranged to be energized in series by current passing through the contacts.

g 6. In an electric switch, in combinatiomrelatively movable contacts similarly-wound coils connected to the tacts respectively and arranged in coamar relationship therewith, said coils forming a. portion of the switch circuit when the contacts are closed. i

7. In switch apparatus for opening and closing an electric circuit, contact elements disposed for movement into and out 01" contacting relation with respect to each other, and means forming part of such circuit and being operable upon the completion thereof by contacting action of said elements to provide a field wherein the lines of force thereof are unidirectional with respect to both elements and pass through the same in a direction substantially normal to their respective contacting surfaces.

8. In switch apparatus for opening and closing an electric circuit, contact elements disposed for'movement into and out of contacting relation with respect to each other; and coils associated respectively with said elements and forming part of such circuit being operable upon the completion thereof by contacting action of said elements to provide a current path of helical form wherein each of the convolutions of the helical path extends in the same direction as the others and wherein the axis of such path is substantially normal to the contacting surfaces of said elements.

9. In switch apparatus for opening and closing an electric circuit, contact elements disposed for movement into and out of contacting relation with respect to each other, and means forming part of such circuit and being operable upon the completion thereof by contacting action of said elements to effect application to said apparatus of an electrodynamic force urging said elements into contacting relation and whereinsuch force is proportional to the variation-of current in such GOTTFRIED BRI IHLMANN. 

